The consumption of biscuits in China is increasing yearly, but soft wheat, the material for making biscuits, has been in shortage for a long time. American soft wheat is of stable quality and excellent processing performance, and is welcomed by Chinese processing enterprises. This study on the interannual dynamic change of grain quality and the relationship between quality indexes of American soft red winter and soft white wheat in multiple years could provide the reference for Chinese weak gluten wheat production.

Based on the quality data of soft wheat published by American Wheat Association from 1999 to 2019, the correlation analysis and cluster analysis were used to analyze the relationship among wheat grain, flour, dough and baking quality, and the fitness of American soft wheat quality to the existing weak gluten wheat standard in China was also analyzed.

For grain quality, the mean value of grain protein content (GPC, %), hardness (H), test weight (TW, g·L^-1) and 1000-grain weight (TKW, g) of soft red winter wheat was lower than that of soft white wheat. The annual variation of quality indexes showed: H>TKW>GPC>TW. For flour quality, the wet gluten content (WG, %) of two kinds of soft wheat were about 22%. Four kinds of solvent retention capacity (SRC, %) of soft red winter wheat were higher than or similar to soft white wheat, while the WG, sedimentation value and four kinds SRC of soft red winter wheat had lower variation coefficients. For dough quality, the development time, stability time (ST, min), alveograph P, L, W value and extensograph parameters of soft red winter wheat were lower than those of soft white wheat, and their water absorption (WA, %) was about 52%. The variation coefficients of farinograph, alveograph and extensograph parameters of soft red winter wheat were lower. According to Chinese weak gluten wheat standard GB 17320-2013, the reaching rate of GPC, WG and ST in soft red winter wheat were 100%, 100% and 57.1%, respectively. The reaching rates of GPC, WG and ST in soft white wheat were 90.5%, 95.2% and 38.1%, respectively. Under GB 17893-1999, GPC, WG and ST of two kinds of soft wheat were as follows: GPC<WG<ST, and the reaching rate was less than 70%. Correlation analysis of soft white wheat showed that there was a significantly negative correlation between TKW and GPC, WG, sucrose SRC, H and WG, while a significant positive correlation was found between GPC and WG, sucrose, lactic acid SRC, sucrose SRC and alveograph W, lactic acid SRC and extensibility. Biscuits diameter was negatively correlated with GPC, W and sucrose SRC, and positively correlated with TW, Biscuits spread ratio was negatively correlated with sucrose SRC. Correlation analysis of soft red winter wheat showed that the protein content of flour was positively correlated with WG and ST, and biscuits diameter was negatively correlated with TW and W.

Soft red winter wheat had softer grain texture, smaller grain weight and weaker dough strength. The TW, flour extraction rate (FER, %) and WA were stable in different years. Soft red winter wheat fit the requirements of Chinese weak gluten wheat standard better, with higher reaching rate. The Chinese weak gluten wheat standard was too strict on GPC, WG and ST. The correlation among quality indexes of soft white wheat was more significant than soft red winter wheat. The GPC, sucrose SRC and alveograph W were significantly correlated with other quality indexes, which could be used to evaluate the quality of weak gluten wheat. The GPC, WG, sedimentation value and alveograph L of soft wheat were similar, which could be classified into same category.